Construct a triangle and place points on the bisectors of the three sides. These will be the first three points on the nine-point circle.

Now construct the altitudes and place points at the places where the altitudes intersect the sides of the triangle. These three points will be the next three points of ther nine-point circle.

Now only show the parts of the altitudes that go from the vertex to the point of concurrency.

Now show the midpoints of these altitude portions. They will be the last three points of the nine-point circle.

To obtain the centre of the nine-point circle, join the midpoints of the altitude portions and create the orthocentre of this new triangle.

Back to Main Page

Back to Concurrency Page